Corrosion resistance of fly ash-based geopolymer in hydrochloric and sulfuric acid solutions

Abstract Currently, there is a growing interest in the use of industrial waste as a raw material in obtaining and developing new products in order to meet technological and environmental demands. Fly ash, for example, when in contact with an alkaline medium, forms inorganic polymers or geopolymers, which have properties comparable to ordinary Portland cement (OPC), but are capable of reducing up to 95% of CO2 emission into the atmosphere. In this study, the corrosion resistance of a geopolymer produced by the alkaline activation of fly ash type F was evaluated in 3%, 6%, and 9% hydrochloric and sulfuric acid solutions for up to 28 days. The materials showed an average loss in terms of compressive strength of approximately 29,8% and 39,5% after 28 days of immersion in HCl and H2SO4, respectively. The immersion in HCl showed divergent results due to the formation of NaCl crystals around the microstructure of the material.